A wide variety of artificial oxygen carriers have been developed over the past century. Many of these are based on perfluorocarbon emulsions, some of which have been used since World War II. Despite moderate success for particular applications, current emulsions exhibit a number of weaknesses which can limit their effectiveness and potential applications. Some of these limitations include limited stability, unacceptable toxicity, undesirable host reactions, and non-optimal oxygen release characteristics. For example, most current commercial perfluorocarbon emulsions have a half-life in vivo of less than an hour, and often less than fifteen minutes. Thus, stability remains one of the primary deficiencies of current perfluorocarbon emulsion compositions. Current surfactant-stabilized dispersion droplets tend to coalesce via Ostwald ripening ultimately leading to breakdown of the emulsions.
A promising new application of artificial oxygen carriers is maintaining tissue oxygen levels in bioreactors, a little-explored topic with profound implications for improving the relevance of in vitro models. Moreover, the challenge of exchanging oxygen, nutrients, and wastes typically limits the thickness of engineered tissues to a few hundred micrometers. Therefore, improved artificial oxygen carriers and methods of using such carriers continue to be sought.